prep 一道题求助

cyx3271

Amy's grade was 90th percentile of the 80grades for her class, of the 100 grades from another class, 19 were higher than Amy's score and the rest were lower . If no other grade was the same as Amy's grade, then Amy's grade was what percentile of the grades of the tweo classes combined?
答案是92nd  第一题啊 我真的是看不懂 做不出

cyx3271

刚刚打错了 是92 哈

cyx3271

已经得到答案哈！